Resin emulsion



PatentedApr. 9, 1940- UNITED STATES PATENT OFFICE RESIN EMULSION William J. Thackston, Haddon Heights, N. J.,

asslgnor to 'Riihm & Haas Company, Philadelphla, Pa.

No iii-swing. Application December 15, 1937,

., Serial No. 179.865

Claims. (Cl. 260-29) This invention relates to a process of preparing ther et al. Patent 2,019,865 granted November 5, stable aqueous emulsions of reactive urea-formal- 1935, and the Ludwig application Serial No. dehyde condensation products of the organic 95,845 filed August 13, 1936. Resins made in acsolvent soluble type that are obtainable by concordance with the method of this invention are' 5 densing urea and formaldehyde or dimethylol preferred. The second procedure is illustrated by s urea in an alcoholic solvent. the Ludwig application Serial No. 139,919 filed The object of the invention is to provide stable April 30, 1937. In this process the urea-formalemulsions of reactive urea-formaldehyde condehyde reaction is started in aqueous solution, densation products. A further object is to prothereafter dehydrated and the condensation convide a process by which emulsions of this type tinued slowly in an alcoholic solution. As is dis- 10 can be prepared. closed in the patents referred to, other anhydrous When urea and formaldehyde or their addition q ds can e sed in P ace Of alcohols but the products, the methylol ureas, are condensed they product thus obtained is not as clear and stable pass through a series 01 stages that terminates a resin s ar th d wi h al h ls.

in an insoluble, infusible, relatively inert, resin- These resins are normally keted dissolved 1| ous mass. In thefirst stages of condensation, in the alcoholic solve t n which they a p the reaction product is highly soluble in water. pared. Preferably they are used in that state In later stages the water solubility gradually but if desired part of the solvent can be removed diminishes until water has at most only a slight it y be in p t p ed w th a diflerent 2o swelling eflect. When the point is reached at solvent such as toluene. Where the alcoholic 50 which the product no longer swells in water, solvent s p t y soluble in water a suflieient condensation is substantially complete. In order e s should Present o sure that the resin to produce organic solvent soluble ,urea formalis not thrown out of solution during emulsiflcadehyde resins processes have been developed by. tion or, in the alternative, the water used may be which the condensationis carried o t in the pressaturated with the partially soluble alcohol. 28

ence of an alcoholic solvent. Condensation proden the resin is prepared in water soluble alucts of this type when dissolved in paint and cohols the uncombined alcohol should be replaced varnish solvents make excellent coating compo- W a Water i le lven sitions. As emulsifying agent may be used ammoniacal 30 It has now been found that solutions of these casein. sulfonated s c as k y red o 80 organic solvent soluble urea-formaldehyde water soluble cellulose ethers, long chain ammodensation products while still in a very reactive Ilium salts, Particularly the g a n quaterstage are not afiected by water and can be emuly ammonium a Twiteheil reagent. e esified therein to give emulsions having a variety, The use Of emmonieeal Casein a d similar alkaof technical applications for which neither the 11118 a g reagents are not recommended for '85 aqueous solutions nor organic solvent solutions their alkaline eheraeter interferes W th the curare suitable. ing of the resin when applied and must be coun- The urea-formaldehyde d t t which teracted by the addition of acid. The water solthis principle a b applied are th organic uble cellulose ethers, particularly methyl cellu- 40 solvent soluble condensates that are prepared in 1086. When Used in sllfiieieht q y. give thick 40 alcohols, preferably monohydric alcohols. These m i ns 1 xcellent stability but th are s m condensates are belived to be ethers of the parwhat dlflicult to dilute. When used in quantities tially condensed urea-formaldehyde reaction such that a readily dilutable emulsion is obproduct in which the alcohol etherifies-a number tained, the emulsion is stable in the concentrated of the methylol groups before complete condensaform ut tl s r he quickly W en dilu 45 tion takes place. Although they may be com- The long ch in q rn y n m s s were pletely dehydrated they are still reactive and found suitable for dilute dispersions which howmay be converted to the insoluble infusible state ever, were less stable than those obtained with by heating under conditions that break the ether methyl c ul s but w n att pts w e mad linkage. There are two ways by which they can to obtain more concentrated ones the phases re- 50 be prepared. In one paraformaldehyde and versedto awater-in-oil type emulsion. The best urea, or their equivalent, dimethylol urea, are emulsions however, were obtained by combincondensed in the presence of an acid catalyst ing a water soluble cellulose ether, particularly and an anhydrous alcohol. This method is 11- methyl cellulose, with a long chain ammonium lustrated by the Lauter Patent 1,633,337, the Lusalt. This combination gave perfectly stable concentrated emulsions easily convertible to dilute emulsions that would not settle even after long standing. The unique emulsifying ability of this particular combination is an important feature of the invention.

In this combination the cellulose ether may be a water soluble methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, or similar water soluble ether. The long chain ammonium salts are preterably the quaternary substituted ammonium salts in which one of the substituents contains a chain of more than nine carbon atoms, preferably sixteen or more, such as- Dimethyl phenyl cetyl ammonium chloride Dimethyl benzyl cetylammonium sulfate Dimethyl benzyl oleyl ammonium chloride Dimethyl benzyl lauryl ammonium chloride Diethyl methallyl cetyl ammonium chloride Diethyl benzyl lauryl ammonium phosphate Dimethyl cetyl amine hydrochloride Dimethyl benzyl cetyl ammonium acetate Dimethyl benzyl cetyl ammonium oleate Dimethyl benzyl cetyl ammonium stearate The cellulose ether can be used in amounts varying from 0.6 parts to 4 parts and the ammonium salts from 0.5 to 4 parts per 100 parts of resin. Greater quantities of ammonium salts may be used but without advantage. Very good results are obtained using 2 parts of methyl cellulose and tional water saturated if desirable with the alcohol in which the resin is dissolved, then adding a water solution of the long chain quaternary ammonium salt, and finally beating in the resin. Other processes can, of course, be used. It is frequently possible to add all the ingredients together and beat them into an emulsion although some times this results in a water-in-oil emulsion.

Also, the emulsifying agent can be added to the.

resin instead of to the water. Instead of saturating the water used with the alcoholic solvent 9. sufficient excess may be added to the resin to provide for some passing into solution.

The following examples are given for purposes of illustration, it to be understood however, that the invention is not limited to them.

Example 1.-50 parts by weight of a 4% aqueous solution of methyl cellulose was diluted with 98 parts water saturated with butanol. 3 parts of dimethyl cetyl benzyl ammonium chloride dissolved in a mixture of three parts ethyl alcohol and 6 parts water were added with stirring. 100 parts of a urea-formaldehyde resin solution containing approximately 60% solids and made by condensing one mol of urea with two of paraformaldehyde in butanol solution using 0.1% of formic acid as condensing agent and reacted at the boiling point of the mixture with constant separation of water until approximately two mols of water were liberated, was slowly added while the mixture was being vigorously beaten so that the resin was emulsified as rapidly as it was run in. After all the resin was added beating was continued for an equal period to insure uniform and thorough emulsification.

The pH of the finished product was approximately 6.2-6.4 but a change to pH 8.0 by adding ammonia or to 5.0 by adding acetic acid had no apparent effect on the stability.

Variations in this example that can be made without modification of procedure are: replacing the methyl cellulose with a water soluble ethyl or hydroxyethyl ether of a-cellulnse made by the process of the Powers, Bock and Houck application Serial No. 750,128 filed October 26, 1934, now Patent No. 2,087,549 granted July 20, 1937; replacing of dimethyl cetyl benzyl ammonium chloride with any of the other quaternary ammonium salts heretofore mentioned, and using a plasticized resin consisting for example, of 80 parts urea formaldehyde resin and parts glycerolsebacic acid-castor oil resin. By a similar procedure emulsions may be made using other emulsifying agents as, for example, those heretofore mentioned.

The emulsions thus prepared have a variety of applications in industrial processes. They may be used in the preparation of emulsion paints for they dry down to a continuous film. Or, as disclosed in copending application Serial No. 155,216 filed July 23, 1937, may be used for producing a variety of effects in the finishing of textiles. They may likewise be used in coating paper and other porous materials, such as composition board and leather. They may be readily pigmented or. mixed with color lakes and dyes to produce colored coatings. By dissolving water soluble dyes or dispersing water insoluble dyes in the emulsion the individual particles of resin can be colored.

The emulsions herein disclosed may also be blended with emulsions of other film forming materials such as emulsions of cellulose derivatives, of oil modified alkyd resins, of acrylic and methacrylic ester polymers, and of other synthetic resins, thereby imparting to the films deposited from those emulsions, to a greater or less degree depending upon the proportions used, the distinctive characteristics of the urea-formaldehyde resins.

In utilizing the herein disclosed emulsions as film forming compositions, they are applied by any of conventional methods such as spraying, brushing, spreading or in the treatment of flexible materials by padding the material through the emulsion. The layer thus deposited dries down to a continuous film by evaporation of water and the organic solvent. The resin may then be converted to the insoluble infusible state by baking. To'accelerate the final hardening it is desirable to treat the dried film prior to baking with an acid condensing agent or in the alternative, to add a potentially acid condensing agent such as an ammonium salt of phosphoric acid to the emulsion.

Modifications of the invention will be obvious to those skilled in the art. Insofar as such modifications utilize the principles herein disclosed, it is intended that they shall be covered by the claims.

I claim:

1. A stable, aqueous emulsion, dilutible with water, the internal phase of which consists essentially of a water-insoluble, organic solvent-soluble urea-formaldehyde-alcohol condensate dissolved in a substantially water-immiscible alcohol, the solution of said condensate being emulsitied with a water-soluble cellulose ether and an ammonium salt, substituted by an aliphatic group of at least ten carbon atoms.

2. A stable, aqueous emulsion, dilutible with water, the internal phase of which consists of a water-insoluble, organic solvent-soluble ureaformaldehyde-monohydric alcohol condensate dissolved in a substantially water-immiscible monohydric alcohol, 100 parts of the solution of said condensate being emulsified with between 0.6 and 4 parts of a water-soluble cellulose ether and between 0.5 and 4 parts of a substituted ammonium salt having an aliphatic chain of at least ten carbon atoms.

3. A stable, aqueous emulsion, dilutible with water, the internal phase of which consists of a water-insoluble, organic solvent-soluble urea formaldehyde-butanol condensate dissolved in butanol, 100 parts of the solution of said condensate being emulsified with between 0.6 and 4 parts of a water-soluble methyl cellulose and between 0.5 and 4 parts of dimethylcetylbenzyl ammonium chloride.

4. The process of preparing a stable, aqueous emulsion, dilutible with water, of a water-insoluble, organic solvent-soluble urea-formaldehydealcohol condensate dissolved in a substantially water-immiscible alcohol, which comprises dispersing the alcoholic solution of said condensate in an aqueous solution of a water-soluble cellulose ether and a long chain substituted ammonium salt.

5. The process of preparing a stable, aqueous emulsion, dilutible with water, of a water-insoluble organic solvent-soluble urea-formaldehydebutanol condensate dissolved in butanol, which comprises dispersing 100 parts of the solution of said condensate in an aqueous solution containing between 0.6 and 4 parts of water-soluble methyl cellulose and 0.5 and 4 parts of a quaternary ammonium salt having an aliphatic chain of at least ten carbon atoms.

WILLIAM J. THACKSTON. 

